At our tertiary referral centre we perform video-urodynamics (vUDS) and retrograde leak point pressure (RLPP) tests in men with urinary incontinence following treatment for prostate cancer. Our objective was to determine the incidence of urge urinary incontinence (UUI) and stress urinary incontinence (SUI) in our patient cohort when assessed by vUDS and RLPP to determine the added value (or not) of RLPP.

We retrospectively reviewed the vUDS studies of 313 consecutive male patients of median age 68 years (IQR 61-73) who presented at our centre with urinary incontinence following treatment for prostate cancer between June 2016 and November 2020. 227 patients presented with isolated symptoms of SUI, 13 patients presented with isolated symptoms of UUI and 74 patients presented with mixed UI symptoms of UUI and SUI. Following vUDS we determined if the patient's cause of UI was due to detrusor overactivity (DO) and UUI, urodynamic SUI (uSUI) or a combination of uSUI and UUI. An RLPP test was performed to assess sphincter competence.

A RLPP test measures the pressure of the urethral sphincter mechanism in men. The test is performed in the fluoroscopy suite where images are used to confirm fluid has leaked from the urethra into the bladder. The patient is catheterised using an aseptic technique with a dual lumen catheter positioned in the bulbar urethra. The pressure transducer is zeroed, connected to the pressure line, and then primed with saline. The filling line is connected to the catheter, and then primed with contrast (typically Urografin or Omnipaque). An inflatable cuff is placed around the penile urethra to clamp the urethra and prevent urine flow out the meatus. Liquid is slowly (5ml/min) infused into the bulbar urethra while simultaneously measuring the intra-urethral pressure. An image is taken to ensure the catheter is correctly positioned in the urethra and to confirm no contrast can be seen in the bladder (Figure 1 Bottom Left). The infused liquid is trapped between the sphincter mechanism and the penile cuff. Therefore, as the bulbar urethra fills, the pressure inside the urethra increases. Eventually, the pressure in the bulbar urethra will exceed the sphincter pressure, the liquid will “leak” into the bladder and the measured pressure will plateau. A second image is taken to confirm that the contrast can be seen in the bladder (Figure 1 Bottom Right).

DO was demonstrated in 150 (48%) patients (median pressure 45cmH2O IQR 33-63) with subsequent UUI in 104 (33%) patients (median volume leaked 70ml IQR 25 – 170). SUI was demonstrated in 144 (46%) patients (median volume leaked 11ml IQR 5 – 42), with 62 (20%) of these patients having mixed UI. No UI was demonstrated in 128 (41%) patients. The sphincter closure pressure (Figure 1) was compromised (<70cmH2O) in 94% of patients (median pressure 39cmH2O IQR 31-49) and there was no difference between patients with SUI and UUI (median pressure 36cmH2O IQR 29-42 vs. 36cmH2O IQR 29-44, p=0.51).

While we demonstrated UI in 59% of our patient cohort, sphincter function was compromised in 94% of patients. This would suggest the true incidence of patients suffering from SUI was significantly greater than the 46% demonstrated on urodynamics studies. In addition to the expected urodynamic diagnosis of urodynamic SUI, nearly half of our patient cohort had DO with 1 in 3 patients demonstrating UUI. This highlights the importance of a full urodynamic assessment prior to surgical intervention. While these patients may present with symptoms of SUI, the underlying DO and UUI maybe come more apparent after conventional treatment for symptoms of SUI following prostate cancer treatment.

Sphincter function measured by RLPP was compromised in 94% of patients whilst UI was only demonstrated in 59% of patients during vUDS (33% had UUI and 46% had SUI). Assessment of sphincter function with a RLPP test allowed for definitive diagnosis of SUI and for the patient to progress to definitive UI management without the need for further time consuming and expensive ambulatory urodynamic assessment.